The broad objective of the proposed research is to elucidate the catalytic mechanism of oxynitrilase, an atypical flavoenzyme which catalyzes a non-redox reaction, and to seek a better understanding of the mechanism of electron transfer in reactions where the flavin coenzyme functions as a redox-active catalyst. Studies with oxynitrilase will seek to identify those regions of the coenzyme which are critical in maintaining a catalytically active conformation at the nearby active site. Studies with glycolate oxidase will be conducted to evaluate the mechanism of hydrogen transfer and the role of flavin-substrate adducts as intermediates in catalysis. The proposed research with these enzymes will involve spectroscopic, kinetic and structural analysis of reactions involving use of substrate analogues and modified flavin derivatives.